Facile one-step solvothermal synthesis of active carbon/BiOI microspheres with enhanced visible light-driven photocatalytic activity in the reduction of Cr(vi).

Active carbon/BiOI microspheres were first prepared using a facile one-step solvothermal route from Bi(NO3)3·5H2O, KI, active carbon, and ethylene glycol. The phase structure, morphology, and optical properties of the as-prepared products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, high resolution transmission electron microscopy, and UV-visible diffuse reflectance spectra. HRTEM mapping results showed that within the composites, active carbon particles dispersed well onto BiOI spheres. The apparent variations in binding energies and photocurrent measurement results verified that the interactions between both components are strong. As a consequence, these active carbon/BiOI composites exhibit an enhanced photocatalytic reduction activity of Cr(vi) under visible light (λ > 420 nm) irradiation when compared with pure BiOI. This work can strengthen the application of BiOI-based micromaterials in treating wastewater contaminated by highly toxic and intractable Cr(vi).

Miniaturized ionic liquid dispersive liquid-liquid microextraction in a coupled-syringe system combined with UV for extraction and determination of danazol in danazol capsule and mice serum.

In this study, for the first time, a coupled 1-mL microsyringe system was utilized to perform a miniaturized ionic liquid dispersive liquid-liquid microextraction (IL-DLLME) method. Danazol was extracted and determined via the developed method followed by micro-volume ultraviolet spectroscopy (UV). The extraction process was carried out by the injection of extraction solvent ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate [C8mimPF6] into sample solution (syringe A), and then rapid shoot the solution into syringe B. After that the shooting was repeated several times at a rate of 1 cycle/s. The extraction procedure was induced by the formation of cloudy solution, which was composed of fine drops of [C8mimPF6] dispersed entirely into sample solution with the help of shooting without any dispersive solvent, ultrasonication or high temperature. Several important parameters affecting the extraction efficiency were studied and optimized. Under the optimized conditions, the limit of detection (LOD) was 0.055 µg/mL (capsule) or 0.054 µg/mL (serum) at a signal-to-noise ratio of 3. The calibration curve was linear over the range of 0.62-25 µg/mL. The proposed method was successfully applied to danazol capsule and the real mice serum samples and good spiked recoveries in the range of 90.5-103.4% were obtained. The obtained results of this work were in good agreement with the results of HPLC.

Dispersive solvent-free ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction coupled with HPLC for determination of ulipristal acetate.

In this paper, a simple and efficient ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction (UA IL-DLLME) coupled with high-performance liquid chromatography for the analysis of ulipristal acetate (UPA) was developed. UPA could be easily migrated into 1-octyl-3-methylimidazolium hexafluorophosphate [C8mimPF6] IL phase without dispersive solvent. The research of extraction mechanism showed that hydrophobic interaction force played a key role in the IL-DLLME. Several important parameters affecting the extraction recovery were optimized. Under the optimized conditions, 25-fold enrichment factor was obtained and the limit of detection (LOD) was 6.8 ng mL(-1) (tablet) or 9.3 ng mL(-1) (serum) at a signal-to-noise ratio of 3. The calibration curve was linear over the range of 0.03-6.0 µg mL(-1). The proposed method was successfully applied to the UPA tablets and the real mice serum samples.

Cyclodextrin polymer/Fe3O4 nanocomposites as solid phase extraction material coupled with UV-vis spectrometry for the analysis of rutin.

In this paper, carboxymethyl-hydroxypropyl-ß-cyclodextrin polymer modified magnetic particles Fe3O4 (CM-HP-ß-CDCP-MNPs) were prepared and applied to magnetic solid phase extraction of rutin combined with UV-visible spectrometry detection. The synthesized magnetic particles were characterized by element analysis, Fourier transform infrared spectra, thermal gravimetric analysis, and transmission electron microscopy. Several variables affecting the extraction and desorption of rutin such as pH, the amount of adsorbent, the type and volume of eluent, extraction and desorption time, and temperature were investigated. The maximum adsorption capacity was 67.0 mg g(-1) for rutin with the equilibrium time of 30 min at room temperature, and the adsorbent could be reused for 10 times. A calibration curve was linear in the range of 0.05-8.00 µg mL(-1) with a relative standard deviation of 2.9% (n=5, c=4.0 µg mL(-1)). The limit of detection was 7.0 ng mL(-1). The interaction mechanism between the adsorbent and rutin was also studied. Feasibility of this method was validated by the analysis of rutin tablets and lotus plumule.

[Determination of clopidogrel sulfate in pharmaceutical formulation and biological fluids by extraction spectrofluorimetric method].

A simple and sensitive spectrofluorimetric method has been developed for the determination of clopidogrel sulfate in pharmaceutical formulation and human urine/serum. It is based on the formation of ion-pair complex between clopidogrel sulfate and alizarin red in 0.3 mol x L(-1) hydrochloric acid solution. The ion pair complex was extracted in dichloromethane and the fluorescence intensity was measured at 550 nm after excitation at 428 nm. The various factors influencing ion-pair complex formation and fluorescence determination were discussed. Under the optimized conditions, the fluorescence value showed a good linear relationship with the clopidogrel sulfate concentration ranging from 1.0 to 11.0 µg x mL(-1). The equation of calibration curve was F = 53.32 + 35.01c (µg x mL(-1)), r = 0.994, and the detection limit was found to be 0.11 µg x mL(-1). No interference was observed from common co-existing substances or pharmaceutical excipient. The determination recoveries of clopidogrel sulfate in pharmaceutical formulation and human urine/serum samples were 90.6%-99.3%, 104.6%-109.3%, 96.3%-105.0%, respectively. The method was successfully applied to detect clopidogrel sulfate in clopidogrel sulfate tablet and human urine/ serum. The obtained results of clopidogrel sulfate tablet were in good agreement with the results of HPLC. Therefore, it is concluded that the proposed method is simple, sensitive and rapid for the determination of clopidogrel sulfate in real samples.

ß-Cyclodextrin sensitized spectrofluorimetry for the determination of abiraterone acetate and abiraterone.

A novel spectrofluorimetric method to determine abiraterone acetate and its active metabolite, abiraterone was developed, based on the fact that fluorescence intensity of abiraterone acetate and abiraterone could be enhanced in ß-cyclodextrin (ß-CD) due to the formation of the inclusion complex. The inclusion interaction of ß-CD and abiraterone acetate and the ß-cyclodextrin sensitized spectrofluorimetry was examined. The various factors influencing fluorescence were discussed in details. The results showed that under the optimized conditions, the linear range of calibration curve for the determination of biraterone acetate and abiraterone was 0.20 ~ 6.0 µg/mL, and the detection limit (LOD) was 6.8 (r = 0.997) or 6.6 ng/mL (r = 0.996), respectively. No interference was observed from common co-existing substances or pharmaceutical excipient. The method was successfully applied to the analysis of abiraterone acetate in pharmaceutical formulation and abiraterone in human serum/urine.

Determination of epristeride by its quenching effect on the fluorescence of L-tryptophan.

A rapid, novel spectrofluorimetric method to determine epristeride (EP) in biological fluids and a pharmaceutical formulation was developed, based on the fact that fluorescence intensity of l-tryptophan could be quenched by EP in the medium of pH=9.0. The various factors influencing fluorescence quenching were discussed. The quenching mechanism was investigated with the quenching type, synchronous fluorescence spectra and quantum efficiency. Under the optimized conditions, fluorescence quenching value (ΔF=Fl-tryptophan-FEP-l-tryptophan) showed a good linear relationship with the EP concentration ranging from 0.4 to 12.0 µg/mL. The linearity, recovery and limit of detection demonstrated that the proposed method was suitable for EP determination in biological fluids and EP tablets. The method was successfully applied to the analysis of EP in real samples and the obtained results were in good agreement with the results of the official method.

Study on the interaction between methyl violet and bovine serum albumin by spectral analyses.

In this article the interaction between methyl violet (MV) and bovine serum albumin (BSA) was studied with spectroscopy. The results indicated that the fluorescence intensity of BSA was quenched strongly by MV through a static quenching procedure. The association constants, the number of binding sites and basic thermodynamic parameters were obtained based on fluorescence quenching data. The effect of MV on the conformation of BSA had been investigated with synchronous fluorescence spectroscopy and circular dichroism (CD) spectrum.

[Investigation and application of fluorescence reaction of cerium-L-tryptophan in Triton X-100 microemulsion].

In the present article, the sensitizing effect of Triton X-100 microemulsion media (Triton X-100-M) on the determination of L-tryptophan by fluorescence spectrophotometry was studied, which was based on a strong fluorescence substance produced when L-tryptophan was oxidized by Ce4+ in acid medium. Compared with Triton X-100 micelle (Triton X-100-m), it was found that in the medium of Triton X-100-M the intensity of fluorescence was enhanced by 225 times. Various factors that influence fluorescence determination and interfering ions were examined. The mechanism of sensitizing effect of Triton X-100 microemulsion was also discussed. Under the optimum conditions, the liner range and detection limit are 0.1-1.0 g x mL(-1) and 0.09 microg x mL(-1) (correlation coefficient r = 0.998 4), respectively. The linear equation was F = 342.37+30.45c. The proposed method has been successfully applied to determine food samples.

Fluorescence probe enhanced spectrofluorimetric method for the determination of gatifloxacin in pharmaceutical formulations and biological fluids.

A spectrofluorimetry for the determination of gatifloxacin (GFLX) was developed based on the strong fluorescence of gatifloxacin after adding fluorescence probe yttrium in buffer solution (pH 7.0) and various factors of influencing fluorescence have been researched. Under the optimum conditions, the liner range was 4.00x10(-8) to 1.00x10(-6)gmL(-1) and the detection limit is 3.36x10(-9)gmL(-1) (correlation coefficient r=0.9997), respectively. The relative standard deviation was 1.1% for 11 measurements of 5.6x10(-7)gmL(-1) gatifloxacin standard solution. The mechanism of sensitizing effect of probe was discussed. The proposed method has been successfully applied to determine real samples and the obtained results are in good agreement with the results of HPLC.

The determination of trace lead in Chinese medicinal herbs by flow injection analysis in polyethyleneglycol medium.

In this work, a new flow injection analysis (FIA) for the determination of Pb(2+) in Chinese medicinal herbs was developed. In the buffer solution of borax-NaOH (pH 10.5), Pb(2+) reacted with 2-[(5-bromo-2-pyridyl)-azo]-5-(diethyl-amino)phenol (5-Br-PADAP) to form a complex. The experimental results showed that the sensitivity was enhanced in the presence of polyethyleneglycol-800 (PG-800). The main factors affecting the determination were investigated in detail. Under the optimum conditions, the linear range and detection limit is 0.0-0.3microg/mL and 1.5ng/mL (correlation coefficient r=0.9996), respectively. The linear regression equation is A=-0.005+0.60c (microg/mL). The sample throughout is 10h(-1). Foreign substrates effects were also investigated. The proposed method has been successfully applied to the determination of lead in reference material, goldthread and lepidium seed.

Investigation on the interaction of tetrachloride fluorescein-bovine serum albumin-beta-cyclodextrin and the determination of protein by flow injection analysis.

In this paper, a simple and sensitive flow injection analysis (FIA) for the determination of protein with spectroscopic probe was developed. This method was based on the investigation of the interaction of tetrachloride fluorescein (2,4,5,7-tetrachloro-3,6-fluorandiol)-bovine serum albumin (BSA), the coupling reaction of protein with tetrachloride fluorescein (TCFS) which was used as a spectroscopic probe in the presence of beta-cyclodextrin (beta-CD). The interaction mechanism and the main factors affecting the determination were investigated in details. Under the optimum conditions, the linear range and detection limit were 0.0-28.0 microg mL(-1) and 0.76 microg mL(-1), respectively. The proposed method has been used to determine albumin in serum albumin with satisfactory results.

A fluorescence spectroscopic study of the interaction between epristeride and bovin serum albumine and its analytical application.

A new spectrofluorimetric method to determine epristeride (EP) has been developed, which based on the EP has a strong ability to quench the intrinsic fluorescence of bovine serum albumin (BSA). There was the relationship between the fluorescence quenching intensity of BSA (DeltaF=F(BSA)-F(BSA-EP)) and the concentration EP. The quenching mechanism was investigated with the quenching type, the association constants, the number of binding sites and basic thermodynamic parameters. The method had been successfully applied to the analysis of EP in real samples and the obtained results were in good agreement with the results of official method-HPLC.